Freescale Semiconductor, Inc.
MOTOROLA
Document order number: MC33794/D
Rev 7.0, 04/2004
SEMICONDUCTOR TECHNICAL DATA
Advance Information
33794
Electric Field Imaging Device
The 33794 is intended for applications where noncontact sensing of objects
is desired. When connected to external electrodes, an electric field is created.
ELECTRIC FIELD
IMAGING DEVICE
Freescale Semiconductor, Inc...
The 33794 is intended for use in detecting objects in this electric field. The
IC generates a low-frequency sine wave. The frequency is adjustable by using
an external resistor and is optimized for 120 kHz. The sine wave has very low
harmonic content to reduce harmonic interference.
The 33794 also contains support circuits for a microcontroller unit (MCU) to
allow the construction of a two-chip E-field system.
Features
• Supports up to 9 Electrodes and 2 References
• Shield Driver for Driving Remote Electrodes Through Coaxial Cables
• +5.0 V Regulator to Power External Circuit
• ISO-9141 Physical Layer Interface
• Lamp Driver Output
• Watchdog and Power-ON Reset Timer
• Critical Internal Nodes Scaled and Selectable for Measurement
• High-Purity Sine Wave Generator Tunable with External Resistor
DH SUFFIX
CASE 1291-01
44-LEAD HSOP
DWB SUFFIX
CASE 1390-01
54-LEAD SOICW-EP
ORDERING INFORMATION
Temperature
Range (TA)
Device
MC33794DH/R2
MC33794DWB/R2
-40°C to 85°C
33794 Simplified Application Diagram
Simplified Application Diagram
VPWR
33794
5.0 V
MCU
Analog_IN
Analog_IN
Analog_IN
Analog_IN
Analog_IN
ISO_Tx
ISO_Rx
Watchdog
Reset
Electrode Select
Shield Disable
GPx
VPWR
LAMP_OUT
LAMP_SENSE
VCC
LP_CAP
LEVEL
VDD _MON
PWR_MON
LAMP_MON
ISO_IN
ISO_OUT
WD_IN
RST
A, B, C, D
DIS_SHIELD
LAMP_CTRL
ISO-9141
SIGNAL
VDD
REF_A
REF_B
E1
E9
SHIELD
R_OSC
LAMP_GND
TEST
AGND
GND
This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Motorola, Inc. 2004
ISO-9141 Bus
Monitor (Opt)
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Field Electrodes
(E1 through E9)
Package
44 HSOP
54 SOICW-EP
Freescale Semiconductor, Inc.
A,B,C,D
4
CONTROL
LOGIC
TEST
22 kΩ (Nominal)
5.6 kΩ
OSC
MUX
OUT
E1 – E9
+ REF_A – REF_B
CLK
R_OSC
39 kΩ
DIS_SHIELD
Freescale Semiconductor, Inc...
5.6 kΩ
SHIELD
47 kΩ
MUX
IN
RECT
LPF
VDD
VCC
10 nF
GAIN AND
OFFSET
RST
WD_IN
POR/
WD
VPWR
VCC
REG
AGND
VDD
REG
GND and HEAT SINK
LP_CAP
LEVEL
ATTN
SIGNAL
LAMP_SENSE
LAMP_MON
PWR_MON
VDD_MON
LAMP_GND
LAMP_CTRL
ISO_OUT
ISO_IN
LAMP CKT
ISO-9141
LAMP_OUT
ISO-9141
Figure 1. 33794 Simplified Internal Block Diagram
33794
2
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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VCC
NC
AGND
SHIELD
NC
GND
TEST
E1
E2
E3
E4
E5
E6
E7
E8
E9
REF_A
REF_B
ISO_OUT
ISO_IN
ISO-9141
LAMP_CTRL
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
VPWR
NC
VDD
VDD_MON
CLK
R_OSC
LP_CAP
PWR_MON
LEVEL
SIGNAL
A
B
C
D
DIS_SHIELD
LAMP_MON
LAMP_SENSE
NC
LAMP_OUT
LAMP_GND
WD_IN
RST
HEAT
SINK
GND
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HSOP PIN FUNCTION DESCRIPTION
Pin
Pin Name
Formal Name
Definition
1
VCC
5.0 V Regulator Output
This output pin requires a 47 µF capacitor and provides a regulated 5.0 V for the
MCU and for internal needs of the 33794.
2, 5, 27, 43
NC
No connect
3
AGND
Analog Ground
4
SHIELD
Shield Driver
6, Heat Sink
GND
Ground
7
TEST
Test Mode Control
8–16
E1–E9
Electrode Connections
These are the electrode pins. They are connected either directly or through coaxial
cables to the electrodes for measurements. One of these electrodes can be
selected at a time for capacitance measurement. All of the other unselected
electrodes are grounded by an internal switch. The signal at the selected electrode
pin is routed to the shield driver amplifier by an internal switch. All of the coaxial
cable shields should be isolated from ground and connected SHIELD.
17, 18
REF_A,
REF_B
Reference Connections
These pins can be individually selected like E1 through E9. Unlike E1 through E9,
these pins are not grounded when not selected. The purpose of these pins is to
allow known capacitors to be measured. By using capacitors at the low and high
end of the expected range, absolute values for the capacitance on the electrodes
can be computed.
19
ISO_OUT
ISO-9141 Output
20
ISO_IN
ISO-9141 Input
These pins may be used at some future date and should be left open.
This pin is connected to the ground return of the analog circuitry. This ground
should be kept free of transient electrical noise like that from logic switching. Its
path to the electrical current return point should be kept separate from the return
for GND.
This pin connects to cable shields to cancel cable capacitance.
This pin and metal backing is the IC power return and thermal radiator/conductor.
This pin is normally connected to circuit ground. There are special operating
modes associated with this pin when it is not at ground.
This pin translates ISO-9141 receive levels to 5.0 V logic levels for the MCU.
This pin accepts data from the MCU to be sent over the ISO-9141 communications
interface. It translates the 5.0 V logic levels from the MCU to transmit levels on the
ISO-9141 bus.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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33794
3
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HSOP PIN FUNCTION DESCRIPTION (continued)
Pin
Pin Name
Formal Name
Definition
21
ISO-9141
ISO-9141 Bus
This pin connects to the ISO-9141 bus. It provides the drive and detects signaling
on the bus and translates it from the bus level to logic levels for the MCU.
22
LAMP_CTRL
Lamp Control
This signal is used to control the lamp driver. A high logic level turns on the lamp
23
RST
Reset
This output is intended to generate the reset function of a typical MCU. It has a
delay for Power-ON Reset, level detectors to force a reset when VCC is out-ofrange high or low, and a watchdog timer that will force a reset if WD_IN is not
asserted at regular intervals. Timing is derived from the oscillator and will change
with changes in the resistor attached to R_OSC.
24
WD_IN
Watchdog Input
This pin must be asserted and deasserted at regular interval in order to prevent
RST from being asserted. By having the MCU program perform this operation more
often the allowed time, a check that the MCU is running and executing its program
is assured. If this doesn’t occur, the MCU will be reset. If the watchdog function is
not desired, this pin may be connected to CLK to prevent a reset from being issued.
25
LAMP_GND
Lamp Ground
This is the ground for the current from the lamp. The current into LAMP_OUT flows
out through this pin.
26
LAMP_OUT
Lamp Driver
This is an active low output capable of sinking current of a typical indicator lamp.
One end of the lamp should be connected to a positive supply (for example, battery
voltage) and the other side to this pin. The current is limited to prevent damage to
the IC in the case of a short or surge during lamp turn-on or burn-out.
28
LAMP_SENSE
Lamp Sense
This pin is normally connected to the LAMP_OUT pin. The voltage at this pin is
reduced and sent to LAMP_MON so the voltage at the lamp pin is brought into the
range of the analog-to-digital converter (ADC) in the MCU.
29
LAMP_MON
Lamp Monitor
This pin is connected through a voltage divider to the LAMP_SENSE pin. The
voltage divider scales the voltage at this pin so that battery voltage present when
the lamp is off is scaled to the range of the MCU ADC. With the lamp off, this pin
will be very close to battery voltage if the lamp is not burned out and the pin is not
shorted to ground. This is useful as a lamp check.
30
DIS_SHIELD
Shield Driver Disable
This pin is used to turn off the shield signal. The purpose of doing this is to be able
to detect that the shield signal is not working or the connection to the coax shields
is broken. If either of these conditions exists, there will be little or no change in the
capacitance measured when the DIS_SHIELD is asserted. If the SHIELD output is
working and properly connected, the capacitance of the coax will not be cancelled
when this pin is asserted and the measured capacitance will appear to change by
approximately the capacitance between the center conductor and the shield in the
coax.
34–31
A, B, C, D
Selector Inputs
These input pins control which electrode or reference is active. Selection values
are shown in Table 1, Electrode Selection, page 14.
35
SIGNAL
Undetected Signal
This is the undetected signal being applied to the detector. It has a DC level with
the low radio frequency signal superimposed on it. Care must be taken to minimize
DC loading of this signal. A shift of DC will change the center point of the signal
and adversely affect the detection of the signal.
36
LEVEL
Detected Level
This is the detected, amplified, and offset representation of the signal voltage on
the selected electrode. Filtering of the rectified signal is performed by a capacitor
attached to LP_CAP.
37
PWR_MON
Power Monitor
This is connected through a voltage divider to VPWR. It allows reduction of the
voltage so it will fall within the range of the ADC on the MCU.
38
LP_CAP
Low-Pass Filter Capacitor
33794
4
A capacitor on this pin forms a low pass filter with the internal series resistance
from the detector to this pin. This pin can be used to determine the detected level
before amplification or offset is applied. A 10 nF capacitor connected to this pin will
smooth the rectified signal. More capacitance will increase the response time
unnecessarily.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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HSOP PIN FUNCTION DESCRIPTION (continued)
Pin
Pin Name
Formal Name
Definition
39
R_OSC
Oscillator Resistor
A resistor from this pin to circuit ground determines the operating frequency of the
oscillator. The 33794 is optimized for operation around 120 kHz.
40
CLK
Clock
41
VDD_MON
VDD Monitor
42
VDD
VDD Capacitor
A capacitor is connected to this pin to filter the internal analog regulated supply.
This supply is derived from VPWR.
44
VPWR
Positive Power Supply Input
12 V power applied to this pin will be converted to the regulated voltages needed
to operate the part. It is also converted to 5.0 V (VCC) and 8.5 V (VDD) to power
the MCU and external devices.
This pin provides a square wave output at the same frequency as the internal
oscillator. The edges of the square wave coincide with the peaks (positive and
negative) of the sine wave.
This is connected through a voltage divider to VDD. It allows reduction of the
voltage so it will fall within the range of the ADC on the MCU.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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33794
5
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RST
WD_IN
NC
LAMP_GND
NC
LAMP_OUT
NC
LAMP_SENSE
LAMP_MON
DIS_SHIELD
D
C
B
A
SIGNAL
LEVEL
PWR_MON
LP_CAP
R_OSC
NC
NC
NC
NC
CLK
VDD_MON
VDD
VPWR
1
54
2
53
3
52
4
51
5
50
6
49
7
48
8
47
9
46
10
45
11
44
12
43
13
42
14
41
15
40
16
39
17
38
18
37
19
36
20
35
21
34
22
33
23
32
24
31
25
30
26
29
27
28
LAMP_CTRL
ISO-9414
NC
ISO_IN
NC
NC
NC
ISO_OUT
REF_B
REF_A
E9
E8
E7
E6
E5
E4
E3
E2
E1
TEST
NC
NC
GND
NC
SHIELD
AGND
VCC
SOICW-EP PIN FUNCTION DESCRIPTION
Pin
Pin Name
Formal Name
Definition
1
RST
Reset
This output is intended to generate the reset function of a typical MCU. It has a
delay for Power-ON Reset, level detectors to force a reset when VCC is out-ofrange high or low, and a watchdog timer that will force a reset if WD_IN is not
asserted at regular intervals. Timing is derived from the oscillator and will change
with changes in the resistor attached to R_OSC.
2
WD_IN
Watchdog In
This pin must be asserted and deasserted at regular interval in order to prevent
RST from being asserted. By having the MCU program perform this operation more
often the allowed time, a check that the MCU is running and executing its program
is assured. If this doesn’t occur, the MCU will be reset. If the watchdog function is
not desired, this pin may be connected to CLK to prevent a reset from being
issued.
3, 5, 7,
20–23, 31,
33, 34,
48–50, 52
NC
No connect
These pins may be used at some future date and should be left open.
4
LAMP_GND
Lamp Ground
This is the ground for the current from the lamp. The current into LAMP_OUT flows
out through this pin.
6
LAMP_OUT
Lamp Driver
This is an active low output capable of sinking current of a typical indicator lamp.
One end of the lamp should be connected to a positive supply (for example,
battery voltage) and the other side to this pin. The current is limited to prevent
damage to the IC in the case of a short or surge during lamp turn-on or burn-out.
8
LAMP_SENSE
Lamp Sense
This pin is normally connected to the LAMP_OUT pin. The voltage at this pin is
reduced and sent to LAMP_MON so the voltage at the lamp pin is brought into the
range of the analog-to-digital converter (ADC) in the MCU.
9
LAMP_MON
Lamp Monitor
This pin is connected through a voltage divider to the LAMP_SENSE pin. The
voltage divider scales the voltage at this pin so that battery voltage present when
the lamp is off is scaled to the range of the MCU ADC. With the lamp off, this pin
will be very close to battery voltage if the lamp is not burned out and the pin is not
shorted to ground. This is useful as a lamp check.
33794
6
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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SOICW-EP PIN FUNCTION DESCRIPTION (continued)
Pin
Pin Name
Formal Name
Definition
10
DIS_SHIELD
Shield Driver
This pin is used to turn off the shield signal. The purpose of doing this is to be able
to detect that the shield signal is not working or the connection to the coax shields
is broken. If either of these conditions exists, there will be little or no change in the
capacitance measured when the DIS_SHIELD is asserted. If the SHIELD output
is working and properly connected, the capacitance of the coax will not be
cancelled when this pin is asserted and the measured capacitance will appear to
change by approximately the capacitance between the center conductor and the
shield in the coax.
14–11
A, B, C, D
Selector Inputs
These input pins control which electrode or reference is active. Selection values
are shown in Table 1, Electrode Selection, page 14.
15
SIGNAL
Undetected Signal
This is the undetected signal being applied to the detector. It has a DC level with
the low radio frequency signal superimposed on it. Care must be taken to minimize
DC loading of this signal. A shift of DC will change the center point of the signal
and adversely affect the detection of the signal.
16
LEVEL
Detected Level
This is the detected, amplified, and offset representation of the signal voltage on
the selected electrode. Filtering of the rectified signal is performed by a capacitor
attached to LP_CAP.
17
PWR_MON
Power Monitor
This is connected through a voltage divider to VPWR. It allows reduction of the
voltage so it will fall within the range of the ADC on the MCU.
18
LP_CAP
Low-Pass Filter Capacitor
A capacitor on this pin forms a low pass filter with the internal series resistance
from the detector to this pin. This pin can be used to determine the detected level
before amplification or offset is applied. A 10 nF capacitor connected to this pin will
smooth the rectified signal. More capacitance will increase the response time
unnecessarily.
19
R_OSC
Oscillator Resistor
A resistor from this pin to circuit ground determines the operating frequency of the
oscillator. The 33794 is optimized for operation around 120 kHz.
24
CLK
Clock
25
VDD_MON
VDD Monitor
26
VDD
VDD Capacitor
A capacitor is connected to this pin to filter the internal analog regulated supply.
This supply is derived from VPWR.
27
VPWR
Positive Power Supply
12 V power applied to this pin will be converted to the regulated voltages needed
to operate the part. It is also converted to 5.0 V (VCC) and 8.5 V (VDD) to power
the MCU and external devices.
28
VCC
5.0 V Regulator Output
This output pin requires a 47 µF capacitor and provides a regulated 5.0 V for the
MCU and for internal needs of the 33794.
29
AGND
Analog Ground
This pin is connected to the ground return of the analog circuitry. This ground
should be kept free of transient electrical noise like that from logic switching. Its
path to the electrical current return point should be kept separate from the return
for GND.
30
SHIELD
Shield Driver
32
GND
Ground
35
TEST
Test Mode Control
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
This pin provides a square wave output at the same frequency as the internal
oscillator. The edges of the square wave coincide with the peaks (positive and
negative) of the sine wave.
This is connected through a voltage divider to VDD. It allows reduction of the
voltage so it will fall within the range of the ADC on the MCU.
This pin connects to cable shields to cancel cable capacitance.
This pin and metal backing is the IC power return and thermal radiator/conductor.
This pin is normally connected to circuit ground. There are special operating
modes associated with this pin when it is not at ground.
For More Information On This Product,
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33794
7
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SOICW-EP PIN FUNCTION DESCRIPTION (continued)
Pin Name
Formal Name
Definition
E1–E9
Electrode Connections
These are the electrode pins. They are connected either directly or through coaxial
cables to the electrodes for measurements. One of these electrodes can be
selected at a time for capacitance measurement. All of the other unselected
electrodes are grounded by an internal switch. The signal at the selected electrode
pin is routed to the shield driver amplifier by an internal switch. All of the coaxial
cable shields should be isolated from ground and connected SHIELD.
45, 46
REF_A,
REF_B
Reference Connections
These pins can be individually selected like E1 through E9. Unlike E1 through E9,
these pins are not grounded when not selected. The purpose of these pins is to
allow known capacitors to be measured. By using capacitors at the low and high
end of the expected range, absolute values for the capacitance on the electrodes
can be computed.
47
ISO_OUT
ISO-9141 Output
51
ISO_IN
ISO-9141 Input
This pin accepts data from the MCU to be sent over the ISO-9141 communications
interface. It translates the 5.0 V logic levels from the MCU to transmit levels on the
ISO-9141 bus.
53
ISO-9141
ISO-9141 Bus
This pin connects to the ISO-9141 bus. It provides the drive and detects signaling
on the bus and translates it from the bus level to logic levels for the MCU.
54
LAMP_CTRL
Lamp Control
This signal is used to control the lamp driver. A high logic level turns on the lamp.
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Pin
36–44
33794
8
This pin translates ISO-9141 receive levels to 5.0 V logic levels for the MCU.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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MAXIMUM RATINGS
All voltages are with respect to ground unless otherwise noted.
Rating
Symbol
Value
Unit
Peak VPWR Voltage
VPWRPK
40
V
Double Battery
VDBLBAT
V
26.5
1 Minute Maximum TA = 30°C
V
ESD Voltage
VESD1
VESD2
±2000
±200
TSTG
-55 to 150
°C
Operating Ambient Temperature
TA
-40 to 85
°C
Operating Junction Temperature
TJ
-40 to 150
°C
Junction-to-Ambient (Note 3)
RθJ-A
41
Junction-to-Case (Note 4)
RθJ-C
0.2
Junction-to-Board (Note 5)
RθJ-B
3.0
TSOLDER
260
Human Body Model (Note 1)
Machine Model (Note 2)
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Storage Temperature
°C/W
Thermal Resistance
Lead Soldering Temperature (for 10 Seconds)
°C
Notes
1. ESD1 performed in accordance with the Human Body Model (CZAP = 100 pF, RZAP = 1500 Ω).
2.
ESD2 performed in accordance with the Machine Model (CZAP = 200 pF, RZAP = 0 Ω).
3.
Junction temperature is a function of on-chip power dissipation, package thermal resistance, mounting site (board) temperature, ambient
temperature, air flow, power dissipation of other components on the board, and board thermal resistance. In accordance with SEMI G3887 and JEDEC JESD51-2 with the single layer board horizontal.
Indicates the average thermal resistance between the die and the case top surface as measured by the cold plate method (MILSPEC 883
Method 1012.1) with the cold plate temperature used for the case temperature.
Thermal resistance between the die and the printed circuit board per JEDEC JESD51-8. Board temperature is measured on the top surface
of the board near the package.
4.
5.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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9
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STATIC ELECTRICAL CHARACTERISTICS
Characteristics noted under condition -40°C ≤ TJ ≤ 150°C. Voltages are relative to GND unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
4.75
5.0
5.25
8.075
8.5
8.925
Unit
VOLTAGE REGULATORS
VCC
5.0 V Regulator Voltage
7.0 V ≤ VPWR ≤ 18 V, 1.0 mA ≤ IL ≤ 75 mA, CFILT = 47 µF
V
VANALOG
Analog Regulator Voltage
9.0 V ≤ VPWR ≤ 18 V, CFILT = 47 µF
V
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VCC OUT-OF-RANGE VOLTAGE DETECTOR
5.0 V Low Voltage Detector
VLV5
4.0
4.52
4.72
V
5.0 V High Voltage Detector
VHV5
5.26
5.55
5.83
V
5.0 V Out-of-Range Voltage Detector Hysteresis
VHYS5
–
0.05
–
V
Input Low Level (Note 6)
VIFINLO
0.30
0.33
–
V/V
Input High Level (Note 6)
VIFINHI
–
0.53
0.7
V/V
Input Hysteresis (Note 6)
VIFINHYS
–
0.2
–
V/V
Output Low (Note 6)
VIFOLO
–
–
0.2
V/V
Output High (Note 6)
VIFOHI
0.8
–
–
V/V
40
–
–
–
58
–
60
90
120
–
–
8.0
–
–
1.0
100
–
–
–
–
5.4
ISO-9141 COMMUNICATIONS INTERFACE
VIFZ
Output Breakdown
IOUT = 20 mA
V
Ω
RIFON
Output Resistance
IOUT = 40 mA
IIFLIM
Current Limit
Sinking Current with VOUT < 0.3 VPWR IN
mA
µs
TIFDLY
Output Propagation Delay
Out to ISO-9141, CLOAD = 20 pF
ISO IN
VIFOLO
Logic Output Low
ISINK = 1.0 mA
V
µA
IIFPU
Logic Output Pull-Up Current
VOUT = 0 V
TIFDLY
Input to Output Propagation Delay
ISO-9141 to ISO_IN, RL = 10 kΩ, CL = 470 pF, 7.0 V ≤ VPWR ≤ 18 V
µs
Notes
6. Ratio to VPWR.
33794
10
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STATIC ELECTRICAL CHARACTERISTICS (continued)
Characteristics noted under condition -40°C ≤ TJ ≤ 150°C. Voltages are relative to GND unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
–
–
3.0
–
-20
–
Unit
ELECTRODE SIGNALS
Total Variance Between Electrode Measurements (Note 7)
ELVVAR
All CLOAD = 15 pF
Electrode Maximum Harmonic Level Below Fundamental (Note 8)
ELHARM
5.0 pF ≤ CLOAD ≤ 100 pF
dB
ELTXV
Electrode Transmit Output Range
V
1.0
–
8.0
0
–
9.0
–
–
5.0
1.0
–
8.0
SDIN
0
–
9.0
V
SWVON
–
–
1.5
V
CMOS Logic Input Low Threshold
VTHL
0.3
–
–
VCC
Logic Input High Threshold
VTHH
–
–
0.7
VCC
Voltage Hysteresis
VHYS
–
0.06
–
VCC
VIN = VCC
10
–
50
VIN = 0 V
-5.0
–
5.0
DETRO
–
50
–
kΩ
LP_CAP to LEVEL Gain
AREC
3.6
4.0
4.4
AV
LP_CAP to LEVEL Offset
VRECOFF
-3.3
-3.0
-2.7
V
5.0 pF ≤ CLOAD ≤ 100 pF
Freescale Semiconductor, Inc...
%
Receive Input Voltage Range
RXV
Grounding Switch on Voltage
SWVON
ISW = 1.0 mA
V
V
SHIELD DRIVER
SDTXV
Shield Driver Output Level
0 pF ≤ CLOAD ≤ 500 pF
Shield Driver Input Range
Grounding Switch on Voltage (Note 9)
V
LOGIC I/O
µA
IIN
Input Current
SIGNAL DETECTOR
Detector Output Resistance
Notes
7. Verified by design. Not tested in production.
8. Verified by design and characterization. Not tested in production.
9. Current into grounded pin under test = 1.0 mA.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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STATIC ELECTRICAL CHARACTERISTICS (continued)
Characteristics noted under condition -40°C ≤ TJ ≤ 150°C. Voltages are relative to GND unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
–
1.75
3.5
0.7
–
1.7
–
–
1.4
40
–
–
Unit
LAMP DRIVER
On Resistance
Current Limit
ILDLIM
VOUT = 1.0 V
On-Voltage
Freescale Semiconductor, Inc...
A
VLDON
IOUT = 400 mA
Breakdown Voltage
Ω
RLDDSON
IIN = 400 mA
V
VLDZ
IOUT = 100 µA, Lamp Off
V
VOLTAGE MONITORS
LAMP_MON to LAMP_SENSE Ratio
LMPMON
0.1950
0.20524
0.2155
V/V
PWR_MON to VPWR Ratio
PWRMON
0.2200
0.2444
0.2688
V/V
VDD_MON to VDD Ratio
VDDMON
0.45
0.5
0.55
V/V
33794
12
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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DYNAMIC ELECTRICAL CHARACTERISTICS
Characteristics noted under condition -40°C ≤ TJ ≤ 150°C. Voltages are relative to GND unless otherwise noted.
Characteristic
Symbol
Min
Typ
Max
Unit
OSC Frequency Stability (Note 10), (Note 11)
f STAB
–
–
10
%
OSC Center Frequency
f OSC
–
120
–
2nd through 4th Harmonic Level
–
–
-20
5th and Higher
–
–
-60
–
-20
–
–
4.5
–
t PER
9.0
–
50
ms
Watchdog Time-Out Period
t WDPER
50
68
250
ms
Watchdog Reset Hold Time
t WDHLD
9.0
–
50
ms
t SCB
3.0
–
–
ms
OSC
R_OSC = 39 kΩ
OSCHARM
Harmonic Content (Note 10)
Freescale Semiconductor, Inc...
kHz
dB
SHIELD DRIVER
Shield Driver Maximum Harmonic level below Fundamental (Note 10)
10 pF ≤ CLOAD ≤ 500 pF
Shield Driver Gain Bandwidth Product (Note 10)
dB
SDHARM
SDGBW
Measured at 120 kHz
MHz
POR
POR Time-Out Period
WATCHDOG
LAMP DRIVER
Short Circuit to Battery Survival Time
Notes
10. Verified by design and characterization. Not tested in production.
11. Does not include errors in external reference parts.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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Table 1. Electrode Selection
Freescale Semiconductor, Inc...
PIN/SIGNAL
33794
14
D
C
B
A
Source (internal)
0
0
0
0
E1
0
0
0
1
E2
0
0
1
0
E3
0
0
1
1
E4
0
1
0
0
E5
0
1
0
1
E6
0
1
1
0
E7
0
1
1
1
E8
1
0
0
0
E9
1
0
0
1
REF_A
1
0
1
0
REF_B
1
0
1
1
Internal OSC
1
1
0
0
Internal OSC after 22 kΩ
1
1
0
1
Internal Ground
1
1
1
0
Reserved
1
1
1
1
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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SYSTEM/APPLICATION INFORMATION
Freescale Semiconductor, Inc...
INTRODUCTION
The 33794 is intended for use in detecting objects using an
electric field. The IC generates a low radio frequency sine
wave. The frequency is set by an external resistor and is
optimized for 120 kHz. The sine wave has very low harmonic
content to reduce potential interference at higher harmonically
related frequencies. The internal generator produces a
nominal 5.0 V peak-to-peak output that is passed through an
internal resistor of about 22 kΩ. An internal multiplexer routes
the signal to one of 11 pins under control of the ABCD input
pins. A receiver multiplexer simultaneously connected to the
selected electrode routes its signal to a detector, which
converts the sine wave to a DC level. This DC level is filtered
by an external capacitor and is multiplied and offset to increase
sensitivity. All of the unselected electrode outputs are
grounded by the device. The current flowing between the
selected electrode and the other grounded electrodes plus
other grounded objects around the electrode causes a voltage
drop across the internal resistance. Objects brought into or out
of the electric field change the current and resulting voltage at
the IC pin, which in turn reduces the voltage at LP_CAP and
LEVEL.
A shield driver is included to minimize the effect of
capacitance caused by using coaxial cables to connect to
remote electrodes. By driving the coax shield with this signal,
the shield voltage follows that of the center conductor,
significantly reducing the effective capacitance of the coax and
maintaining sensitivity to the capacitance at the electrode.
The 33794 is made to work with and support a
microcontroller. It provides two voltage regulators, a PowerON-reset/out-of-range voltage detector, watchdog circuit,
lamp driver and sense circuit, and a physical layer ISO-9141
communications interface.
BLOCK DIAGRAM COMPONENTS
Refer to Figure 1, 33794 Internal Block Diagram, page 2, for
a graphic representation of the block diagram information in
this section.
OSC
This section generates a high purity sine wave. The center
frequency is controlled by a resistor attached to R_OSC. The
normal operating frequency is around 120 kHz. A square wave
version of the frequency output is available at CLK. Timing for
the Power-ON Reset and watchdog (POR/WD) circuit are
derived from this oscillator’s frequency.
MUX OUT
This circuit directs the output of the sine wave to one of nine
possible electrode outputs or two reference pins. All unused
pins are automatically grounded. The selected output is
controlled by the ABCD inputs.
MUX IN
This circuit connects the selected electrode, reference, or
one of two internal nodes to an amplifier/detector. The
selection is controlled by the ABCD inputs and follows the
driven electrode/reference when one is selected.
RECT
The rectifier circuit detects the level from MUX IN by
offsetting the midpoint of the sine wave to zero volts and
inverting the waveform when it is below the midpoint. It is
important to avoid DC loading of the signal, which would cause
a shift in the midpoint voltage of the signal from the MUX IN.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
LPF
The rectified sine wave is filtered by a low pass function in
the LPF formed by an internal resistance and an external
capacitance attached to LP_CAP. The nominal value of the
internal resistance is 50 kΩ. The value of the external capacitor
is selected to provide filtering of noise while still allowing the
desired settling time for the detector output. A 10 nF capacitor
would allow 99% settling in less than 5.0 ms.
GAIN and OFFSET
This circuit multiplies the detected and filtered signal by a
gain and offsets the result by a DC level. This results in an
output range that covers 1.0 V to 4.0 V for capacitive loading
of the field in the range of 10 pF to 100 pF. This allows higher
sensitivity for a digital-to-analog converter with a 0 V-to-5.0 V
input range.
ATTN
This circuit passes the undetected signal to SIGNAL for
external use.
LAMP CKT
This section controls the operation of the LAMP_OUT pin.
When LAMP_CTRL is asserted, LAMP_OUT is pulled to
LAMP_GND. If one side of an indicator lamp or LED (with
appropriate current setting resistor) is connected to a positive
voltage source and the other is connected to LAMP_OUT, and
LAMP_GND is connected to ground, the lamp will light. This
circuit provides current limiting to prevent damage to itself in
the case of a shorted lamp or during a high-surge condition
typical of an incandescent lamp burnout.
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ISO-9141
VDD REG
This circuit connects to an ISO-9141 bus to allow remote
communications. ISO_IN is data from the bus to the MCU and
ISO_OUT is data to drive onto the bus from the MCU.
This is a regulator for analog devices that require more than
5.0 V. This is used by the device and some current is available
to operate op-amps and other devices. By having this higher
voltage available, some applications can avoid the need for a
rail-to-rail output amplifier and still achieve the 0 V-to-5.0 V
output for a digital-to-analog converter input. VDDMON is a
divided output from VDD, which allows a 0 V-to-5.0 V ADC to
measure VDD.
Freescale Semiconductor, Inc...
POR/WD
This circuit is a combined Power-ON Reset and watchdog
timer. The RST output is held low until a certain amount of time
after the VCC output has remained above a minimum operating
threshold. If VCC falls below the level at any time, RST is pulled
low again and held until the required time after VCC has returned
high. An overvoltage circuit is also included, which will force a
reset if VCC rises above a maximum voltage. The watchdog
function also can force RST low if too long an interval is allowed
to pass between positive transitions on WD_IN.
CONTROL LOGIC
This contains the logic that decodes and controls the MUXes
and some of the test modes.
VCC REG
This circuit converts an unregulated voltage from VIN to a
regulated 5.0 V source, which is used internally and available
for other components requiring a regulated voltage source.
APPLICATION INFORMATION
The 33794 is intended to be used where an object’s size and
proximity are to be determined. This is done by placing
electrodes in the area where the object will be. The proximity of
an object to an electrode can be determined by the increase in
effective capacitance as the object gets closer to the electrode
and modifies the electric field between the electrode and
surrounding electrically common objects. The shape and size of
an object can be determined by using multiple electrodes over
an area and observing the capacitance change on each of the
electrodes. Those that don’t change have nothing near them,
and those that do change have part of the object near them.
The voltage measured is an inverse function of the
capacitance between the electrode being measured and the
surrounding electrodes and other objects in the electric field
surrounding the electrode. Increasing capacitance results in
decreasing voltage. The value of series resistance (22 kΩ) was
chosen to provide a nearly linear relationship at 120 kHz over a
range of 10 pF to 100 pF.
The measured value will change with any change in
frequency, series resistance, driving voltage, or detector
sensitivity. These can change with temperature and time. The
proper use of REF_A and REF_B will allow much of the
changes to be compensated for.
A typical measurement algorithm would start by measuring
the voltage for two known value capacitors (attached to REF_A
and REF_B). The value of these capacitors would be chosen to
33794
16
be near the minimum and maximum values of capacitance
expected to be seen at the electrodes. These reference
voltages and the known capacitance values are then used with
the electrode measurement voltage to determine the
capacitance seen by the electrode. This method can be used to
detect short- and long-term changes due to objects in the
electric field and significantly reduce the effect of temperatureand time-induced changes.
The 33794 does not contain an ADC. It is intended to be
used with an MCU that contains one. Offset and gain have been
added to the 33794 to maximize the sensitivity over the range
of 0 pF to 100 pF. An 8-bit ADC can resolve around 0.4 pF of
change and a 10-bit converter around 0.1 pF. Higher resolution
results in more distant detection of smaller objects.
DC loading on the electrodes should be avoided. The signal
is generated with a DC offset that is more than half the peak-topeak level. This keeps the signal positive above ground at all
times. The detector uses this voltage level as the midpoint for
detection. All signals below this level are inverted and added to
all signals above this level. Loading of the DC level will cause
some of the positive half of the signal to be inverted and added
and will change the measurement.
If it is not possible to assure that the electrodes will always
have a high DC resistance to ground or a voltage source, a
series capacitor of about 10 nF should be connected between
the IC electrode pins and the electrodes.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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+12 V
47 µF
Indicator
Lamp
0.1 µF
VCC
VPWR
10 nF
LAMP_OUT
LP_CAP
VCC
LEVEL
VDD
VDD_MON
PWR_MON
LAMP_MON
ISO-9141
LAMP_SENSE
Analog_IN
Analog_IN
Analog_IN
Analog_IN
Analog_IN
Freescale Semiconductor, Inc...
33794
MCU
ISO_Tx
ISO_IN
ISO_Rx
ISO_OUT
Watchdog
10 kΩ
47 µF
ISO-9141 Bus
Monitor (Optional)
SIGNAL
WD_IN
REF_A
RST
REF_B
LAMP_CTRL
Reset
GPx
10 pF
100 pF
LAMP_GND
E1
1
E2
2
E9
9
TEST
Electrode Select
A, B, C, D
4
Shield Disable
DIS_SHIELD
Field
Electrodes
SHIELD
GND
R_OSC
AGND
39 kΩ
Figure 2. Typical Application Diagram
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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PACKAGE DIMENSIONS
DH SUFFIX
44-LEAD HSOP
PLASTIC PACKAGE
CASE 1291-01
ISSUE O
PIN ONE ID
h
X 45 °
E3
E2
4X
E5
44
4X
D
0.325
Freescale Semiconductor, Inc...
D1
D3
D2
e
42X
1
22
23
EXPOSED
HEATSINK AREA
B
E1
E4
A
22X
E
BOTTOM VIEW
bbb M C B
Y
H
DATUM
PLANE
b1
A A2
c1
c
C
SEATING
PLANE
b
aaa
L1
q
W
W
L
A1
bbb C
(1.600)
DETAIL Y
33794
18
M
C A
SECTION W-W
GAUGE
PLANE
NOTES:
1. CONTROLLING DIMENSION: MILLIMETER.
2. DIMENSIONS AND TOLERANCES PER ASME
Y14.5M, 1994.
3. DATUM PLANE -H- IS LOCATED AT BOTTOM
OF LEAD AND IS COINCIDENT WITH THE
LEAD WHERE THE LEAD EXITS THE PLASTIC
BODY AT THE BOTTOM OF THE PARTING
LINE.
4. DIMENSIONS D AND E1 DO NOT INCLUDE
MOLD PROTRUSION. ALLOWABLE
PROTRUSION IS 0.150 PER SIDE.
DIMENSIONS D AND E1 DO INCLUDE MOLD
MISMATCH AND ARE DETERMINED AT
DATUM PLANE -H-.
5. DIMENSION b DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.127 TOTAL IN
EXCESS OF THE b DIMENSION AT MAXIMUM
MATERIAL CONDITION.
6. DATUMS -A- AND -B- TO BE DETERMINED AT
DATUM PLANE -H-.
7. DIMENSION D DOES NOT INCLUDE TIEBAR
PROTRUSIONS. ALLOWABLE TIEBAR
PROTRUSIONS ARE 0.150 PER SIDE.
DIM
A
A1
A2
D
D1
D2
D3
E
E1
E2
E3
E4
E5
L
L1
b
b1
c
c1
e
h
q
aaa
bbb
MILLIMETERS
MIN
MAX
3.000 3.400
0.025 0.125
2.900 3.100
15.800 16.000
11.700 12.600
0.900 1.100
--- 1.000
13.950 14.450
10.900 11.100
2.500 2.700
6.400 7.300
2.700 2.900
--- 1.000
0.840 1.100
0.350 BSC
0.220 0.350
0.220 0.320
0.230 0.320
0.230 0.280
0.650 BSC
--- 0.800
0°
8°
0.200
0.100
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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DWB SUFFIX
54-LEAD SOICW-EP
PLASTIC PACKAGE
CASE 1390-01
ISSUE B
10.3
5
7.6
7.4
9
C
1
B
2.65
2.35
52X
54
0.65
Freescale Semiconductor, Inc...
PIN 1 INDEX
4
9
B
18.0
17.8
CL
B
27
28
A
5.15
54X
2X 27 TIPS
0.3
SEATING
PLANE
0.10 A
A B C
NOTES:
1. ALL DIMENSIONS ARE IN MILLIMETERS.
2. DIMENSIONING AND TOLERANCING PER ASME
Y14.5M, 1994.
3. DATUMS B AND C TO BE DETERMINED AT THE PLANE
WHERE THE BOTTOM OF THE LEADS EXIT THE
PLASTIC BODY.
4. THIS DIMENSION DOES NOT INCLUDE MOLD FLASH,
PROTRUSION OR GATE BURRS. MOLD FLASH,
PROTRUSION OR GATE BURRS SHALL NOT EXCEED
0.15 MM PER SIDE. THIS DIMENSION IS DETERMINED
AT THE PLANE WHERE THE BOTTOM OF THE LEADS
EXIT THE PLASTIC BODY.
5. THIS DIMENSION DOES NOT INCLUDE INTERLEAD
FLASH OR PROTRUSIONS. INTERLEAD FLASH AND
PROTRUSIONS SHALL NOT EXCEED 0.25 MM PER
SIDE. THIS DIMENSION IS DETERMINED AT THE
PLANE WHERE THE BOTTOM OF THE LEADS EXIT
THE PLASTIC BODY.
6. THIS DIMENSION DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL NOT CAUSE THE LEAD WIDTH TO EXCEED
0.46 MM. DAMBAR CANNOT BE LOCATED ON THE
LOWER RADIUS OR THE FOOT. MINIMUM SPACE
BETWEEN PROTRUSION AND ADJACENT LEAD
SHALL NOT LESS THAN 0.07 MM.
7. EXACT SHAPE OF EACH CORNER IS OPTIONAL.
8. THESE DIMENSIONS APPLY TO THE FLAT SECTION
OF THE LEAD BETWEEN 0.1 MM AND 0.3 MM FROM
THE LEAD TIP.
9. THE PACKAGE TOP MAY BE SMALLER THAN THE
PACKAGE BOTTOM. THIS DIMENSION IS
DETERMINED AT THE OUTERMOST EXTREMES OF
THE PLASTIC BODY EXCLUSIVE OF MOLD FLASH,
TIE BAR BURRS, GATE BURRS AND INTER-LEAD
FLASH, BUT INCLUDING ANY MISMATCH BETWEEN
THE TOP AND BOTTOM OF THE PLASTIC BODY.
A
R0.08 MIN
C
C
0 ° MIN
0.25
GAUGE PLANE
(1.43)
A
8°
0°
0.30 A B C
0.9
0.5
SECTION B-B
0.1
0.0
4.8
4.3
(0.29)
4.8
4.3
0.30
0.25
0.30 A B C
BASE METAL
(0.25)
0.38
0.22
6
0.13
M
PLATING
A B C
8
SECTION A-A
ROTATED 90 ° CLOCKWISE
VIEW C-C
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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Freescale Semiconductor, Inc...
Freescale Semiconductor, Inc.
Information in this document is provided solely to enable system and software implementers to use Motorola products. There are no express or implied
copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document.
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee
regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product
or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be
provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating
parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. Motorola does not convey any license
under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for
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claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated
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respective owners.
© Motorola, Inc. 2004
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852-26668334
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